How to determine the number of floors of high-rise residential buildings?
The common floors of high-rise residential buildings are 1 1, 18, 26 and 33. How are these figures determined? In addition, there will be manned elevators above the seventh floor. Why the seventh floor instead of the sixth or eighth floor?
The following are the answers of different netizens.
First, the result of the balance between norms and interests
1 1 floor: there must be a manned elevator above the seventh floor, and there must be a fire elevator above the 1 1 floor, and the fire door must reach Grade B, so it is the building of 1 1 floor that can earn more and spend less (the seventh floor without elevator is mostly the school dormitory floor).
18 floor: emergency exits are required for floors above 1 18, and two exits will be provided for floors above1118, and the stairwell above1/8 should be closed. So it's 18 floor to make money, with less money and less trouble.
26th floor: 19 floor is the first type of fire-proof building (previously it was the second type), the rhythm of two fire-proof elevators (it is also said that there are three elevators and one fire-proof) and two smoke-proof stairs.
Nowadays, many rapidly developing cities will have residential height restrictions, such as 80 meters (airport height restrictions, microwave channels, urban skyline control, urban planning requirements, etc.). 80/3=26 floors, so it is the number of floors that meet the residential restrictions and maximize benefits.
Floor 33: What about those without the above restrictions? What about going up again? According to the General Principles for the Design of Civil Buildings, when the building height exceeds 100m, both residential buildings and public buildings are super high-rise buildings. (More than 40 storeys are required abroad), and 33 storeys 100 meters or more is another standard in terms of specification and safety. Therefore, it is the 33rd floor that makes more money and has less trouble.
B. Wei Zhaoming mentioned the requirements of various codes for building floors. What are these specifications based on to determine the number of building floors? Why is a staircase 1 1 instead of 10 or 12? This is something not mentioned in the specification, but its principle is also very simple. Let me elaborate on it.
There are many sources to determine the demarcation point of building floors. There are requirements for urban planning indicators and environmental impact, and there are requirements for considering human physiological factors, fire protection factors and structural factors.
First, the restrictions of urban planning.
First of all, the building height of a city is controlled by urban planning. For example, if the planning conditions require multi-storey buildings, the dormitory cannot be built to more than seven floors. The planning requires the height to be controlled below 100 meters, so the design will be about 30 floors. If you have a house in the north, the distance is 50 meters. According to the requirements of the sunshine distance in the south 1: 1, your height can't exceed 50 meters, and one floor can cover 16 floors. In the north, if the sunshine interval is 1: 1.2, then only 50/3.11.2 is needed to make up the 13 layer. In addition, now that the land price is high, developers will try their best to strive for higher floor area ratio and saleable area, which also leads to higher and higher housing. From the perspective of economic benefits, the plot ratio index of land is the decisive factor to determine the number of buildings.
Second, people's physiological conditions
This mainly affects the dividing point between multi-storey and high-rise buildings. Multi-storey buildings can be built without elevators. Therefore, considering the physiological limitation of people climbing stairs, elevators should be designed for houses with more than seven floors, and the height of railings should be higher than one meter to ensure safety. There must be an elevator in the office above the seventh floor of the dormitory and above the fifth floor.
Third, the fire facilities factors
This is a condition that has the greatest influence on the critical point of high-rise residential buildings. Simply put, it is the physical strength of firefighters and the height of the ladder truck that determine the common story relationship in residential buildings.
There are two important principles to ensure the fire safety of buildings: one is to ensure the safe evacuation of personnel, which is generally guaranteed by two-way evacuation. So that in case of fire, one end can run out. The second is that fire-fighting facilities can ensure that firefighters put out the fire. In fact, there is another principle, which is to take fire prevention measures to reduce combustible materials and prevent the fire from spreading. But it has little to do with the topic, so I won't go into details.
The fire fighting facilities of the city fire brigade rely on fire engines (ladder trucks for saving people) outdoors and fire hydrants indoors. Then the limit of firefighters and fire engines determines the height limit of high-rise buildings. Experiments have been done, and firefighters can climb less than ten floors quickly when they are armed to their teeth, and their physical strength can no longer guarantee to put out the fire immediately. Therefore, the fire elevator should be set after several floors to protect the physical strength of firefighters. However, the height of ordinary fire-fighting ladder truck is limited, so the highest floor of an ordinary elevator+a staircase is also determined, 1 1. Otherwise, the building will catch fire and firefighters can't climb it at all.
It is difficult to directly rescue a building fire above 18 floor (18*3m=54m) when the height of a common ladder truck is about 50m. This is also required by the fire code. 18 floor is a hurdle. The floors above 18 need to be equipped with smoke-proof stairwells to strictly ensure evacuation safety.
If there is a fire in the middle of a building over 100 meters, it is difficult for people on the upper part to rescue it (not every city has helicopters). Therefore, the code requires that public buildings (about 30 floors) exceeding 100 meters must be provided with refuge floors. Moreover, the height of the first refuge floor should not be higher than 45 meters, which is convenient for fire rescue. /kloc-residential buildings over 0/00 meters, due to the non-public nature, shall be handled according to local requirements. (generally not)
The above are probably some principles of the number of floors stipulated in the Code for Fire Protection Design of High-rise Civil Buildings. These floors with height conversion are roughly the source of the specific figures asked by the subject.
C elevators and stairwells have a great influence on the interests of all parties.
Unless required by Party A, the designer shall carry out architectural design within the limits permitted by the specification. This advantage is that the cost of Party A is reduced to the greatest extent under the condition of meeting the specifications. After all, people design fees and make more money for others.
The number of floors of residential buildings is often set by the upper limit allowed by the code. This can reduce the building area as much as possible, and correspondingly reduce the excavation area of foundation pit/reduce the number of piles; Expand the greening or square area; Expand the space between buildings; Optimize sunshine conditions and so on.
Of course, dissatisfaction with the floor ceiling also happens from time to time. The reason may be wonderful, because the area was miscalculated before the design, and the designed floor was simply cut off and not built. There are also some conventional reasons, such as unsatisfactory sunshine, planning height limit, geomantic omen, local regulations and so on.
Article 3. 1.2 of General Principles for Design of Civil Buildings (GB50352-2005) classifies houses according to floors:
The first to third floors are low-rise residential buildings.
The fourth to sixth floors are multi-storey houses.
The seventh to ninth floors are medium and high-rise residential buildings.
Ten floors and above are high-rise residential buildings;
Almost all the specifications of various restrictions on residential buildings are based on this classification standard.
For example:
Code for Residential Building GB50368-2005
Article 5.65438 +0.5
The clear height of balcony railings for six floors and below should not be less than 1.05m, and that for seven floors and above should not be less than 1. 10m.
Article 5.3.3
The entrance platform width of seven-story and above residential buildings should not be less than 2.00m m.
There are too many detailed rules like the above, and the examples are different. But for the construction and installation costs, these can be ignored and have no impact at all.
Indeed, it has a great influence on the indexes related to the interests of all parties, such as construction and installation costs, room acquisition rate, etc., mainly elevators and stairwells:
1. Elevator
Code for Residential Design (GB50096-20 1 1)
6.4. 1:
In any of the following circumstances, an elevator must be set:
1when the height from the entrance floor to the outdoor design floor of a residential building with seven or more floors exceeds 16m; 6.4.2:
/kloc-for residential buildings with 0/2 floors and above, each building shall have at least 2 elevators, of which 1 elevator can accommodate stretchers.
Code for fire protection design of high-rise civil buildings GB50045-95
6.3. 1:
The following high-rise buildings should be equipped with fire elevators:
6.3. 1.3 12 floors and above apartment buildings and verandahs.
So instead of building an elevator to achieve the sixth floor, you just want to build an elevator to achieve the eleventh floor. Elevators increase costs and affect room rates. Generally, there is no elevator as Party A's selling point. ..
Step 2: stairs
Code for fire protection design of high-rise civil buildings GB50045-95
6.2.3. 1 Units with 11th floor and below may not have closed stairwells, but the doors leading to the stairwells shall be Class B fire doors.
6.2.3.212 and 18 apartment buildings should be provided with closed staircases.
6.2.3.319 and above units shall be provided with smoke-proof stairs.
6.2.4 The corridor-style residence with the 11th floor and below shall be provided with a closed stairwell; Corridor houses with more than eleven floors should have smoke-proof stairs. Open stairs, open stairwells, closed stairwells and smoke-proof stairwells are vertical evacuation escape routes with higher and higher fire protection codes.
Therefore, if you don't want to set up a closed staircase, you can do it on the eleventh floor, and if you don't want to set up a smoke-proof staircase, you can do it on the eighteenth floor. The smoke-proof stairwell also needs to be equipped with a smoke-proof front room and a positive pressure air supply duct, both of which need to occupy public area to reduce the room rate. In China, there is no public area at all, which is also a part of my family; The improvement of security level is also a kind of protection for me.
In addition: residential building code GB50368-2005.
9.2.2 The maximum allowable number of floors for a four-level fire-resistant residential building is three, nine for a three-level fire-resistant residential building and 18 for a two-level fire-resistant residential building.
The fire resistance grade is gradually improved, and the requirements for components are correspondingly improved.
As for the 33rd floor, it can only be completed if the total height of the building does not exceed1100mm. ..
More than 100m is a super-high-rise building. Regardless of the strict specifications for various professions, it is enough for all stakeholders to drink a pot just by setting up a refuge floor. Who can stand the pool area?
In fact, if the story is 2.8m high, it can be 35 stories, but now the industry basically follows the story of 2.9m high, and the 33 rd story is just the customary practice left by the story of 3m high at that time.
As for the 26th floor, I don't know.
D. Let's calculate the pool area.
Below the sixth floor, there is only one staircase. The booth on the first floor is only a dozen square meters. One ladder for two households, each household is less than 10 square meters. And it can be transparent from north to south, which is the best apartment.
A stretcher elevator was added to the seventh to eleventh floors, which was five or six square meters more. In addition, pipeline wells and electric wells will be added, and each household will share an increase of five square meters. There are elevators, and the floor area ratio can be greatly improved. It is suitable for some small places where real estate is not very prosperous.
The fire elevator will be located on the 12 floor, but a fire elevator front room and corresponding positive pressure air supply shaft will be added. If there are still two households with one ladder, each household will have to increase the pool of five or six square meters. At this time, the total pool area of each household will exceed 20 square meters. The best 890-square-meter house sold now has an occupancy rate of 75%.
After 18 floor, each unit is required to have two stairwells, and each stairwell should have a front room. At the same time, the number of tube wells will also increase greatly. Basically, it will increase the pool area by 20 to 30 square meters compared with the 18 floor. It is inconceivable to continue a staircase with two households. An 80-square-meter house has a usable area of less than 40 square meters and the occupancy rate is less than 50%. Therefore, there are few houses with one staircase and two households above 18 floors.
More than 26 floors, the structural requirements are improved, the steel content of buildings is greatly improved, and the construction cost of units with the same appearance is greatly increased, which developers are generally unwilling to do.
More than 33 floors, 2.9 meters high, indoor and outdoor height difference 1.2 meters, 97 meters. If there are commercial outlets at the bottom, it is the upper limit of ordinary high-rise buildings. /kloc-there is no current code basis for super high-rise buildings over 0/00 meters. Everything has to cross the river by feeling the stones, and then it will be specially approved by the national overrun research association. This is already a very worthless thing for the house.
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